“It’s important to consider the efficacy of Internet filtering,” said Dr, Nash. “Internet filtering tools are expensive to develop and maintain, and can easily ‘underblock’ due to the constant development of new ways of sharing content. Additionally, there are concerns about human rights violations – filtering can lead to ‘overblocking’, where young people are not able to access legitimate health and relationship information.”

This research follows the controversial news that the UK government was exploring a country-wide porn filter, a product that will most likely fail. The UK would join countries around the world who filter the public Internet for religious or political reasons.

The bottom line? Filters are expensive and they don’t work.

Given these substantial costs and limitations, it is noteworthy that there is little consistent evidence that filtering is effective at shielding young people from online sexual material. A pair of studies reporting on data collected in 2005, before the rise of smartphones and tablets, provides tentative evidence that Internet filtering might reduce the relative risk of young people countering sexual material. A more recent study, analyzing data collected a decade after these papers, provided strong evidence that caregivers’ use of Internet filtering technologies did not reduce children’s exposure to a range of aversive online experiences including, but not limited to, encountering sexual content that made them feel uncomfortable.21 Given studies on this topic are few in number and the findings are decidedly mixed, the evidence base supporting the widespread use of Internet filtering is currently weak.

The researchers “found that Internet filtering tools are ineffective and in most cases [and] were an insignificant factor in whether young people had seen explicit sexual content.”

The study’s most interesting finding was that between 17 and 77 households “would need to use Internet filtering tools in order to prevent a single young person from accessing sexual content” and even then a filter “showed no statistically or practically significant protective effects.”

The study looked at 9,352 male and 9,357 female subjects from the EU and the UK and found that almost 50 percent of the subjects had some sort of Internet filter at home. Regardless of the filters installed, subjects still saw approximately the same amount of porn.

“Many caregivers and policy makers consider Internet filters a useful technology for keeping young people safe online. Although this position might make intuitive sense, there is little empirical evidence that Internet filters provide an effective means to limit children’s and adolescents’ exposure to online sexual material. There are nontrivial economic, informational, and human rights costs associated with filtering that need to be balanced against any observed benefits,” wrote the researchers. “Given this, it is critical to know possible benefits can be balanced against their costs. Our studies were conducted to test this proposition, and our findings indicated that filtering does not play a practically significant protective role.”

Given the popularity – and lucrative nature – of filtering software this news should encourage parents and caregivers to look more closely and how and why they are filtering their home Internet. Ultimately, they might find, supervision is more important than software.